Glass fiber reinforced tape and method of making same



1950 J. STEPHENS 2,951,003

GLASS FIBER REINFORCED TAPE AND METHOD OF MAKING SAME Filed Jan. 20, 1955 INVENTOR. JOSEPH F STEPHENS BYAh'vl-LSQ HTTOPNEV GLASS FIBER REINFORCED TAPE AND METHOD OF MAKING SAME Joseph F. Stephens, Kansas City, Mo., assignor to Gustin- Bacon Manufacturing Company, Kansas City, Mr, a corporation of Missouri Filed Jan. 20, 1955, Ser. No. 482,997

- Claims. ((11. 154-90) My invention relates to a glass fiber reinforced tape and a method of making the same and more particularly to an improved, rapid, inexpensive, and efiicient method of making a glass fiber reinforced tape adapted to be used for strapping packages and the like and to an improved tape resulting from the novel method.

Tape gummed with pressure sensitive, tacky adhesive is well known in the art. Its lineal strength, however, has been such that it could not be employed for binding heavy packages. Steel straps have been largely used for this purpose. These straps are expensive to manufacture, difficult to apply to packages, and require special tools for their removal. Patent 2,674,556, granted April 6, 1954, on an application of Walter H. Pahl et al., discloses a longitudinally reinforced gummed tape in which glass filament yarns are positioned in a pressure sensitive adhesive and sandwiched between two layers of paper, one of which is gummed. In the manufacture of such yarns and in the composition of such yarns a form suitable for inclusion in such tape, it has been customary to form the yarn used as reinforcing material by collecting or aggregating them into a filament strand and then passing them over an applicator pad which applies a sizing in order to integrate the strand. The strand may comprise, for example, 204 filaments having average diameters from =five and fifty microns. The aggregated strand is wound upon a small drum which is known in the art as a forming tube. A traverse is employed to lay the strand of filaments in a pattern which will permit the unwinding of the strand from the drum or forming tube. The filament strand thus accumulated on the forming tube is then passed through a twister frame, in which operation the forming tube acts as the feeder package. The twisted strand is accumulated on the twister tube after having been given the desired twist during the process. After the yarns have been collected on the twister tubes, a plurality of the tubes are mounted on a creel and the various yarns or twisted strands are fed therefrom to compose a parallel lay upon a large spool which is commonly known as a warp beam. The yarns collected on the warp beam are then fed to a coating machine which applies a thermosetting synthetic resin which is adapted to integrate the parallel strands into a sheet of material. This sheet of material can be cut into tapes or ribbons and sandwiched between paper layers, one of which is gummed, as shown in the Pahl patent referred to above, or adhered to a sheet of cellophane by means of pressure sensitive, tacky adhesive, forming a glass fiber reinforced, pressure sensitive tape. If desired, the coating material may be pressure sensitive, normally tacky adhesive.

It will be readily appreciated that the manufacture of the reinforced tape is complicated, requires a large number of steps and operations, and hence is quite expensive to carry out. The tying of the ends of the strands passing from theforming tubes to the twister tubes requires time and expense. If the twisting operation is dispensed with, it is necessary to tie the ends of the ma- 2,951,003 Patented Aug. 3t), 1960 terial fed to the twister tubes into the warp beam in order to compose a warp beam of suificient length. Typically, only two or three pounds of fiber are accumlated on each forming tube. This necessitates a twisting or tying operation in order to produce a warp beam of any considerable length.

Besides the foregoing disadvantages, it is necessary to control the tension 'of a large number of strands which compose the warp beam. The equal tension of the strands, furthermore, must be maintained in feeding the filaments from the warp beam through the coating step. If the strands are of unequal tension, the resulting material will be correspondingly weakened and the maximum strength which could be achieved for the weight of material employed is not reached.

One object of my invention is to provide 'a novel method of making a glass fiber reinforced tape in which the disadvantages of the prior art are obviated.

Another object of my invention is to provide a glass fiber reinforced tape which is homogeneous throughout any reasonable, predetermined length.

A further object of my invention is to provide a method of making glass fiber reinforced, pressure sensitive tape in a simple, convenient, expeditious, and economical manner.

A further object of my invention is to provide a method of making a glass fiber reinforced tape in which the glass fibers are disposed parallel to each other and under a substantially uniform and equal tension.

Other and further objects of my invention will appear from the following description.

In general my invention contemplates the provision of a comparatively large diameter drum on which I position a sheet of cellophane or other appropriate surfacing sheet which is to form the backing element of my tape. The drum is adapted to be mounted for simultaneous rotation and axial movement. A high-strength adhesive is then spread over the backing sheet and permitted to become partially dry so that it is tacky. This drum, thus prepared, that is, with the backing sheet deposited thereon and the backing sheet coated with a high-strength adhesive, is then used to draw parallel filaments of glass fibers from a spinning box. The entire surface of the drum is wound with a glass fiber strand composed of a number of glass filaments drawn directly from the spinning box onto the tacky surface of the partially dried adhesive. After the adhesive has set, or has been caused to dry by heat or the like, the surface of the glass fibers are coated with a normally tacky, pressure sensitive adhesive. The drum is then removed and placed in a cutting fixture. A helical path for the cutting tool through the assembly is then described either by moving the tool to describe a helix or by rotating the drum and advancing it with respect to the cutting tool. In this manner a considerable length of glass fiber reinforced, pressure sensitive tape is produced. It is to be understood, of course, that a sheet of paper or other surfacing material may be applied to the adhesive while it is still in the tacky condition and the outside of this paper gummed to produce a gummed strapping tape. The salient feature of my method, it will be seen, lies in the method which can be employed to produce many kinds of adhesive tapes which have been reinforced by means of glass fibers.

In the accompanying drawing which forms part of the instant specification and which is to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

Figure 1. is a diagrammatic view showing the step of winding a strand formed of a plurality of glass filaments already been positioned.

Figure 2 is a diagrammatic view showing the step of cutting the tape from the drum after the glass fiber strand has been coated with adhesive.

Figure 3 is a perspective ViEW of a strip of the glass fiber reinforced, pressure sensitive tape formed by my method with the end of the tape in section.

More particularly referring now to the drawing, 1 mount a backing sheet 10, which is to form the body of the tape, upon a drum 7.2. The tape may be of cellophane, Saran, or the like, if the adhesive of the tape is to be a normally tacky, pressure sensitive adhesive. The normally tacky adhesive will adhere to the cellophane or Saran less strongly than to most surfaces to which it is to be applied. It a gumrned strapping tape is desired as the end product, the backing sheet may be formed of a heavy kraft paper having a weight of from fifty to seventy-five pounds per ream. If cellophane is to be the backing sheet of the drum or the body of the tape, then a normal cellophane sheet from 300 points to 500 points, or more, may be employed.

The backing sheet it may be secured to the drum 12 in any appropriate manner. The drum is mounted upon a bushing 14 and secured thereto by appropriate gib keys 16; The drum, it will be observed, will now rotate with the bushing. The bushing 14 is internally threaded and is mounted upon a lead screw 13 which is supported in any appropriate manner, as, for example, by pillar blocks 20. Que end of the drum 12 is provided with a gear 22 which meshes with an elongated pinion 24. The pinion 24 is carried by a shaft 26 and is adapted to be driven by any appropriate means, such as a motor (not shown). The drum 12 may advantageously be four feet in diameter and four feet in length. The drum is adapted to be driven at speeds of between 400 and 1,200 revolutions per minute, giving peripheral speeds of between about 5,000 and 15,000 feet per minute. At these drawing speeds, glass fibers may be drawn directly from the spinning box 28 into which molten glass is fed. The glass filaments being drawn from the spinnerettes of the spinning box 28 are gathered by a loop 30 to form a strand of parallel fibers 32. If desired, adhesive may be applied to the strand at this point.

Preferably, before the glass fibers are drawn onto the drum, the drum is coated with a suitable, high strength adhesive which may be an air setting, hot or cold glue, or may be a thermoplastic or thermosetting synthetic resin. It is only necessary that the adhesive used be such that it will adhere to the backing sheet. After the backing sheet positioned on the drum is coated with an adhesive and this adhesive is permitted to become in a partially set, partially cured, or tacky state, the strand of glass fibers is positioned at the end of the drum adjacent the gear 22. The shaft 26 is then driven to rotate the elongated pinion 24 in the direction shown by the arrow in Figure 1 in order to rotate the drum in the direction shown by its arrow. The drum will rotate the bushing 14 and advance the drum upon the lead screw 18 to the left as viewed in Figure l, winding the strand 32, composed of a number of filaments of glass, say 204 in number, in parallel relation and with uniform tension upon the tacky adhesive positioned on the backing sheet 10 which is mounted on the drum. The pitch of the lead screw 18 is quite shallow so that the filaments will form a helix with a very small angle with a plane normal to the axis of rotation of the drum. Normally, one layer of glass filament strand is sufficient for most uses. if desired, after one layer of glass filament strand is wound on the drum, a second layer of high strength glue can be applied over the layer of glass fiber strand and the direction of rotation of the elongated pinion 24 reversed and the process repeated in the opposite direction. In this case two helices will be present upon the drum, one forming an angle with the plane normal to the axis of rotation of the drum in one direction and the other forming a like angle in the opposite direction,

I a .thermosetting one, the drum is subjected to the necessary heat to set the adhesive. The drum is then coated with a pressure sensitive adhesive which may be of any appropriate formula or type. An advantageous formula is as follows:

Ingredient: Percent by weight Latex crepe 13.09 Zinc oxide 15.93 #10 wood rosin 6.25 Antioxidant 0.13 Volatile solvent 64.60

The antioxidant may be a condensation product of acetone and aniline. The volatile solvent may advantageously be heptane. The above adhesive is a normally tacky, pressure sensitive type. Other examples of an appropriate pressure sensitive adhesive may be found in Kellgren et al. Patent 2,444,830. The pressure sensitive adhesive may be applied in any appropriate manner. The drum may be mounted on another bushing 40 and secured thereto by appropriate gib keys 42. Bushing 40 is mounted on a load screw 44, which has a much greater pitch than the lead screw 18. The pitch of the lead screw 44- is such as to give the desired width to the finished glass fiber reinforced tape. The backing sheet 10, with the layer or layers of parallel filaments 32 glued thereto, is coated with the pressure sensitive adhesive,

either before it ,is placed upon the bushing 46 or after it is so mounted. If desired, the layer of glass fibers 32 may be coated while the drum is on the bushing 40. This is accomplished by removing the gib 42 and driving the drum 12 through its gear 22 by means of another elongated rack 46 mounted on a shaft 48. The shaft 48 is adapted to be driven at any appropriate speed. Before the drum 12 is rotated the gib keys 42 are removed. It is understood, of course, that there may be one gib key 42 at each end of the drum. Means not shown may be provided for immobilizing the bushing 40. With the gib keys 42 removed and the bushing 40 immobilized, the drum 12 will then rotate freely on the bushing. The pressure sensitive adhesive can readily be applied while the drum is thus rotating.

After the drum has been coated with a pressure sensitive adhesive layer 50, we are ready to cut the sheet on the drum into a tape or tapes. A shaft 52 is mounted on any suitable framework (not shown) adjacent the drum. The shaft carries a pivoted lever 53, to which is secured an axle 54. A rotary cutting wheel 56 is carried by the axle 54-. The framework which carries shaft 52 is stationary during the cutting operation but may be adjusted longitudinally of the drum. A spool 58 is carried upon a shaft 60, which may be driven by any appropriate means, to rotate the spool in the direction of the arrow. With a drum four feet in diameter, each hoop of tape will only be approximately twelve and one-half feet in length. Assuming further that the finished tape, which is indicated generally by the reference numeral 80, was an inch in width, we could get approximately 580 feet of continuous tape by cutting the tape along a helical path.

To obtain a continuous tape, I insert the gib key 42 to permit the bushing 40 to feed along the lead screw 44, the pitch of which is such as to advance one inch for each revolution of the drum 12. The shaft 48 is driven by any appropriate means (not shown) and the cutting wheel 56 is pressed against the tape assembly mounted on the drum 12. The direction of rotation of the shaft 48 is such as to rotate the elongated pinion 46 and the drum 12 in the direction of the arrows in Figure 2. This will drive the drum 12 to the left. The finished tape 80 is wound upon a spool 58, as shown in Figure 2.

It is to be understood that the backing sheet, instead of being a preformed sheet of synthetic resin, may be formed from a plastic material in situ upon the drum 12. The drum, for example, may first be coated with a plastic material, such as an epoxy resin. These resins are the reaction products of polyphenolic compounds, such as a bisphenol-A, and an epoxy compound, such as epichlorohydn'n. These resins can be cured with a va riety of hardening agents of the amine or acid type, as is well known to the art. Epoxy resins have excellent wetting power which make them particularly advantageous for use with glass fibers. After the drum is coated with the epoxy resin and the glass filaments are wound upon the coated drum, as described hereinabove, with an amine curing agent, the epoxy resin can be cured in a period varying from fifteen minutes to two hours at temperatures of 160 F. to 300 F. Advantageously, the drum should be coated with a layer of Teflon, or the like, to prevent the cured epoxy resin from adhering to the drum. After the sheet thus formed in situ is cured, it may be coated with a pressure sensitive adhesive and removed from the drum as a tape by means of the cutting step described above.

It will be understood, of course, that instead of coating the glass fiber reinforced tape with a pressure sensitive adhesive, it may be cut from the drum without adhesive and the pressure sensitive adhesive; or the like, applied to one side of the tape after it is cut from the drum.

If it is desired to form a ribbon or tape in a form suitable for the helical winding about a mandrel to form glass fiber reinforced tape, as described in my Patent 2,467,999, I prefer to coat the drum with a plastic material, such as an epoxy resin, wind the strand of glass filaments about the drum, as pointed out above, apply additional layers of epoxy resin and layers of glass filaments until an assembly of the desired thickness is achieved. Instead of setting the resin completely, however, I would prefer setting the resin only suificiently to unite the strands of fibers and then cut a tape from the drum as described above. The tape, with the resin only partially cured, is then wound around a mandrel in a helical pattern to compose the pipe and is then given its final cure or set.

It will be seen that I have accomplished the objects of my invention. I have provided a novel method of making glass fiber reinforced tape in Which the disadvantages of the prior art are obviated and in which I may provide a homogeneous glass fiber reinforced tape of a comparatively long predetermined length in a simple, convenient, expeditious, and economical manner. The glass fibers of my tape do not have to be twisted but are disposed parallel to each other, thus making for a tape of higher tensile strength for a given weight of reinforcing material. I eliminate a great many processing steps whichare necessary in the manufacture of glass fiber reinforced tapes of the prior art. The elimination of the twisting operation is a major forward step in the art.

' The elimination of the elaborate creeling of many twister tubes in the form of a warp beam is a manifest and marked advantage over the prior art. This is true, too, in obviating the tying together of the comparatively small amount of material carried by the twister tubes of the prior art. Besides this, the glass fiber reinforcing material is wound with a predetermined, uniform tension. This eliminates the necessity of the use of a tension control device in the forming of the warp beams. In my method the tape may be out from the drum in either coated or uncoated condition. Besides this, the backing sheet of plastic may be formed on the drum in situ and removed from the drum in partially cured condition, a procedure which is advantageous in the manufacture of plastic pipe and is of advantage for other uses.

It will be understood that certain features and subcombinatious are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It

is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is therefore to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:

l. A method of making tape including the steps of forming a tube of sheet material on a cylindrical member, winding strands of glass filaments upon said tube to cover the tube with a layer of glass filaments, adhering said glass filaments to said tube, then slitting said tube to form a length of glass fiber reinforced tape and stripping said length of tape from the member on which said tube is formed.

2. A method as in claim 1 in which said adhering step is practiced subsequent to said slitting step.

3. A method as in claim 1 in which said slitting step comprises the step of slitting said tube along the locus of a shallow helix.

4. A tape including in combination a plastic strip, a plurality of parallel glass filaments, means for adhering the parallel glass filaments to the strip, said glass filaments being disposed upon said strip with their axes extending in a direction forming an acute angle with respect to the center line of the tape and an adhesive carried by the glass filaments.

5. A tape including in combination a strip of synthetic resin and a plurality of glass filaments embedded in said synthetic resin strip, said glass filaments being disposed in said strip with their axes extending in a direction forming an acute angle with the center line of the tape.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,830 Kellgren et al. July 6, 1948 2,630,157 Smellie Mar. 3, 1953 2,631,957 Francis Mar. 17, 1953 2,664,375 Slayter Dec. 29, 1953 2,673,643 Flank et a1 Mar. 30, 1954 2,674,556 Pahl et al. Apr. 6, 1954 FOREIGN PATENTS 680,657 Great Britain Oct. 8, 1952 871,801 Germany Mar. 26, 1953 

1. A METHOD OF MAKING TAPE INCLUDING THE STEPS OF FORMING A TUBE OF SHEET MATERIAL ON A CYLINDRICAL MEMBER, WINDING STRANDS OF GLASS FILAMENTS UPON SAID TUBE TO COVER THE TUBE WITH A LAYER OF GLASS FILAMENTS, ADHERING SAID GLASS FILAMENT TO SAID TUBE, THEN SLITTING SAID TUBE TO FORM A LENGTH OF GLASS FIBER REINFORCED TAPE AND STRIPPING SAID LENGTH OF TAPE FROM THE MEMBER ON WHICH SAID TUBE IS FORMED. 